Tuning system



May 25, 1937.

T0 AMPLIFIER GRID H. HASSE TUNING SYSTEM Filed Aug. 4, 1954 CONNECT/0N 7'0 TUNER f /OF RECEIVER l Fig.5,

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' H v H b b RAD/0 [IV Fff [R [5 j g,--@ g 5 5 :1 I: :1 a FCI/RED To U [:1 U S41v0 f E! El El ATTORNEY Patented May 25, 1937 UNETED STATES PATENT GFFICE TUNING SYSTEM Hans Hasse, Berlin, Germany,

assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic m. b. H., Berlin, Germany Germany, a corporation of 3 Claims.

This invention relates to tuning systems for radio receiving apparatus. It has been suggested to provide dial arrangements for radio receiving apparatus or the like in which the stations to be received are arranged in predetermined groups such as countries, provinces, transmitting communities, or communities receiving the same program, or the type of program. A special, preferably exchangeably arranged dial with a common indicating device for all groups may be provided for each group of transmitters, Whose individual stations can be distributed in any manner over the respective wave range.

When tuning by means of a group dial not only the transmitters which are contained in this group make their appearance, but also the intermediately disposed transmitters are received. For the purpose of avoiding this drawback, it is proposed to provide filter, screen, or damping means by which a reproduction of the transmitters not contained in the group is avoided. Difiiculties are encountered in this arrangement in that the means for the suppression of undesired transmitters must be changed in addition to the dial for the group.

In accordance with the present invention it is proposed to arrange the means serving for the suppression of the undesired transmitters, at the dial supporting member. In one embodiment of the invention one side of the dial support is provided with a grounded conducting layer having openings at respective places, and a sliding bent member conductingly connected with the grid of the end tube is arranged to slide over the openings upon turning of the tuning member. By suitably arranging the openings the grid of the end tube or of a corresponding tube is grounded so that reproduction of the received transmitters will be suppressed when the tuning member is in a position not corresponding with the tuning of a transmitter of the chosen group of transmitters.

The contact cannot cause disturbance of the reception, since it is open at reception. If the distribution of the waves of the radio transmitter is changed the new contact track is then present on the new dial support. The connection of the bent contact member to the grid of the end tube is of advantage, since in this case only the relatively small amplification of the end tube lies behind the contact so that for this reason a relatively had contact causes very little noise. Moreover, the contact is not charged by direct current. A further advantage of the above described arrangement resides in that it can be easily mounted on existing dials for transmitter groups, without the need of expensive alterations.

For a better understanding of the invention reference is made to the accompanying drawing, in which; 5

Fig. l is a view from the rear of a schematic arrangement embodying the invention,

Fig. 2 is a rear view of a schematic arrangement embodying a modified form of the invention and,

Fig. 3 is a sectional view taken through line 3-3 of Fig. 1 and also showing the amplifier tube connection.

Figure 1 shows the inventive idea in its embodiment given by way of example. Herein a is a film having the various groups of transmitters recorded thereon, and whose rear side is provided with a grounded metal layer In, shown in Fig. 3 as grounded at H. Reference characters 17', b, b" represent, for instance, the names of stations, 0 and c, c, o" designate the respective openings in the metal layer. The windows (1, d, d" formed in film a must coincide with the opening e for the pointer of the steel band 1 coupled to the tuning member, when the tuning is completed. The means used for coupling the flexible band f to the tuning member is not shown for simplicity, such means being well known to those skilled in the art. Reference character 9 designates schematically the contacting bent member connected to the grid of the end tube, and which is moved to and fro together with the steel band 1.

It will be readily seen that the ground connection is interrupted only at the tuning position of one of the three transmitters b, b, b". As shown in Fig. 3 tuning to station I) is indicated, when opening 6 in band 1 is in alignment with window opening (1 of film a. In this position the end of member g is not in contact with the grounded film I 0 and the grid I 3 of the power tube M of the receiver operates at its normal potential, the grid being connected to member 9 by connection l2 as shown. When band 1 is moved during tuning to station I), the end of member 9 at once moves out of the portion 0 onto the grounded metal layer I 0 thereby grounding grid l3 of the last tube of the receiver and maintaining it at ground potential, thus preventing the transmission of the signals from undesired stations passed over during the tuning tostation I)".

When the film band a is displaced for setting a new group of transmitters, the originally adjusted transmitter appears if the contacting member y passes over the station designations b, b, b. In order that this be avoided a double bent member 91 as shown in Fig. 2 is used. The distance of the openings or from the additional contact track h is present only between opening and track, so that in displacing the film band, at least one end of the double bent member or always rests on the metal layer, and consequently the grid of the end tube remains grounded during adjustment of film a from one group of stations to another. Track h is preferably an opening in the metal layer H] on the rear of the film. In this case as in'Fig. 1, the member m is connected to band 1 and it is seen that it remains grounded the entire time it is: moving across the track it and the undesired station positions C1.

What I claim is:

1. In an indicator for atuning means the combination of a member having a plurality of station names arranged in a row and a grounded conducting surface, a window opening adjacent each of said names, a flexible member connected to said tuning means and provided with an indicator adapted to be moved into alignment with said window openings, and means carried by said flexible member and arranged to engage said conducting surface in response to the positioning of said indicator intermediate said window openings.

2. In an indicator for a tuning means, an amplifier tube coupled to said tuning means and having a grid, a member having a plurality of station names arranged in a row, and a grounded conducting surface provided with a plurality of openings corresponding to said station names, a window opening adjacent each of said names, a flexible member connected to said tuning means and provided with an indicator adapted to be 'moved into alignment with said window openings and a member connected to said flexible member and said grid so arranged as to pass intothe opening in said conducting surface in response to the positioning of said indicator opposite one of said window openings.

3. In an indicator for a tuning means, the combination. of a flexible film having a plurality of station marks on its front surface, and a metallic film on its rear surface, a member connected to said tuning means and provided with an indicator, means carried by said member and in engagement with said rear surface and means for breaking said engagement in response to the positioning of said indicator opposite said station marks.

HANS HASSEL. 

